1. Field of the Invention
The present invention relates to the structure of a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device manufactured by a batch transfer molding process.
2. Description of the Background Art
As the method of manufacturing a power semiconductor device, a batch transfer molding process is known in which a plurality of resin-sealed semiconductor devices are collectively formed and then cut (diced) to obtain individual resin-sealed semiconductor devices. The batch transfer molding process enables to improve the reliability of a power semiconductor device and reduce the size and cost thereof.
For example, Japanese Patent Application Laid-Open No. 2002-110885 discloses the method of manufacturing semiconductor devices having a lead frame structure by a batch transfer molding process. Japanese Patent Application Laid-Open No. 2002-110885 describes the technology of providing line-shaped trenches along the dicing lines in the lead frame before cutting a plurality of semiconductor devices that are collectively resin-sealed into pieces through dicing (singulation). This technology lowers the heat generated due to friction in dicing and reduces the occurrence of “burrs” on the cut surface of the lead frame.
In Japanese Patent Application Laid-Open No. 2002-110885, the line-shaped trenches are provided in the lead frame for obtaining advantages in processing, such as ease of cutting and improvement in processing accuracy. According to Japanese Patent Application Laid-Open No. 2002-110885, as shown in FIG. 1, terminal portions cut out from a lead frame are exposed from a molding resin on end surfaces (cut surfaces) of the singulated semiconductor device. Normally, in a semiconductor device having a lead frame structure, a molding resin serves exclusively to insulate terminal portions. Accordingly, with such a configuration, when moisture infiltrates from an interface between the terminal portion exposed at the edge of the semiconductor device and the molding resin, the insulating property of the molding resin may be degraded. The interface peels off in some cases, which may make the package open.
In particular a power semiconductor device is required to withstand high voltage as well as high current, and thus, the reliability of the power semiconductor device may be degraded with the structure in which terminal portions are exposed on the end surfaces of the semiconductor device.